arm64/sysreg: Convert MDSCR_EL1 to automatic register generation

Convert MDSCR_EL1 to automatic register generation as per DDI0616 2023-03.
No functional change.

Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20230419-arm64-syreg-gen-v2-2-4c6add1f6257@kernel.org


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>